What a brave post. Some people with bipolar or BPD or depression may simply be too lost in their illness to know the havoc they’ve wreaked on others, especially those who love them. Some if us try desperately to hide how we are feeling, so as not to worry others, when perhaps, we would recover more quickly if we’d shared earlier.
I commend you and your sister for your honesty and love in dealing with your feelings about your brother’s illness, and wish that you weren’t going through this. To be on edge like that is awful. I hope that you and your mom and his wife can support each other. And I hope that ultimately, your brother helps himself.